There are several prior art methods of transporting unpackaged materials, such as plastic pellets, flour, and sugar, from the manufacturer or producer to the end user. Probably the most popular method is to use hopper railcars, each capable of carrying up to four standard truckloads of material and having a phenolic plastic lining to prevent contamination of the material. The material is shipped via rail to a transfer or "bulk distribution" yard at a desired destination. Here, the hopper railcars are pulled off the main line onto a spur and lined up. In this manner, hopper railcars may be used not only for transportation, but also for storage. When the manufacturer or producer sells a load of product, a common carrier uses a vacuum pneumatic tank trailer to extract a load of product out of the hopper railcar and then transports it to the end user, where it is typically blown into a silo or other appropriate structure for storage.
Although the hopper railcar transportation/distribution method described above has worked well over the years, it suffers certain recognized deficiencies. First, it is relatively expensive, due to the fact that, because the railcars are used for both transportation and storage, the manufacturer must purchase several hopper railcars, pay the freight required to transport each hopper railcar, and then pay a daily fee for each hopper railcar to remain parked on a rail at a remote distribution yard until the goods in the hopper railcar have been sold. In addition, because the hopper railcar has a capacity which is four times that of a standard truckload, only very high quantities of unpackaged materials, to be delivered to a common destination, may be transported by this method. Moreover, it can take several weeks to move a hopper railcar across the country. Therefore, because such hopper railcars are used for both transportation and storage, a manufacturer/producer must have more hopper railcars at its disposal than would be the case if the hopper railcars were transported more quickly.
One alternative to using hopper railcars to transport and store unpackaged materials is to load the material into tank trailers that have been converted into "lift on/lift off" vehicles, which may be transported via flatbed railcar to the designated destination, lifted off the flatbed, hooked on to a truck and delivered to the end user. Such tank trailers are typically transported on dedicated trains; as a result, trailers may be transported from coast to coast in as little as thirty-six (36) hours and, in any event, much less time than it takes to transport a hopper railcar. However, although this method of transportation and distribution enables materials to be transported, stored, and distributed in their original container (i.e., the tank trailer), the investment required in tank trailers is significantly higher than the equivalent capacity in hopper railcars when one considers that it takes four such tank trailers to transport the same amount of material as one hopper railcar. Hence, this method, although rapid, is not particularly cost effective.
Another alternative has been to use a pneumatic container comprising a pressurized vehicle that unloads like a pneumatic trailer. Similar to the tank trailers, such pneumatic containers can be shipped by rail on flatbed cars or by seagoing vessel. To unload the container, a tipping chassis, such as a "BARTLET"-type lift, is used to tip the container so that when the material contained therein is pressurized, the product falls out. However, while pneumatic containers offer advantages similar to those of tank trailers, as described above, they also suffer the same deficiencies; that is, the investment required in tank trailers is significantly higher than the equivalent capacity in hopper railcars. Again, four such trailers are required to carry the same amount of material as a single hopper railcar.
A final alternative has been to use conventional steel shipping containers that are designed to transport packaged products via rail and on seagoing vessels. An advantage of such containers is that they are readily available at a low cost. In addition, because they are certified under federal regulations for transport by rail, they may be adapted for specialized use without first undergoing additional expensive certification procedures. Another advantage is that they may be stacked one on top of another when transported via a railcar. When stored, these containers may be stacked nine high, thus substantially decreasing storage cost. However, because such containers are typically designed to transport packaged, rather than unpackaged materials, it is necessary that they be lined in some fashion to prevent contamination of the unpackaged materials.
One popular method of lining conventional steel shipping containers is to insert a phenolic plastic liner, such as those available from Insta-Bulk, Inc., Houston, Tex., into the containers before filling the containers with the materials to be transported. Although this alternative has become a popular method of shipping unpackaged materials overseas, it is deficient in that such plastic liners do rip, thereby contaminating the unpackaged materials contained therein.
For example, if a worker nails a nail to the floor of the container in order to strap a package into place, and later fails to remove the nail, the nail is likely to puncture the plastic liner once the liner is filled with unpackaged materials (the weight of the unpackaged materials exerts substantial pressure against the nail). In addition, if a worker gouges the floor causing the wood which lines the floor to splinter, the splinter may puncture the plastic liner. Furthermore, in cases where residual unpackaged material, such as a bean, remains in the container when the liner is installed, the residual unpackaged material may cause the plastic liner to rupture.
A still further drawback of the plastic-lined container shipping method is that the liners are not reusable and, once used, must be disposed of in some manner. In some countries, such as Germany, environmental laws forbid the disposal of these liners within their territories. This causes additional inconvenience in that the used liner must then be shipped out of the country for disposal.
A still further drawback is that the plastic liner must be built into the container, a labor-intensive process which involves fabricating a head, a special frame which supports the liner. Because of container defects and the variation in the size of the container, the frame is usually custom fabricated from wood. The weight of the unpackaged materials, 40,000 pounds when fully loaded, creates sufficient stress to break a weak frame, thereby causing significant waste.
In addition, the standard shipping container is designed to carry packaged goods, goods which themselves contain the goods to be transported. The container is not designed to handle a uniform pressure against all the walls of the container such as that which unpackaged goods impose. Rather, it is designed to protect packed materials from the elements, from spillage, and, to a limited extent, from theft.
Further, because the plastic liner is not rigid, and includes only a non-structural plastic sleeve through which product may be loaded and unloaded, special handling is required to mate the sleeve with the loading and unloading device being used. Because of this handling difficulty, the liner cannot be unloaded using a vacuum pneumatic tank truck. Rather, the liner must be unloaded into a secondary container called an air lock. The air lock includes a conveyor system which then transports the unpackaged materials to a storage location, or to a truck.
Further, the plastic-lined shipping container can only be insulated on the exterior surface of the container. This changes the shape of the container, adversely affecting the modularity and stackability of the container.
Therefore, what is needed is an apparatus for enabling unpackaged materials to be shipped in a more timely, economic, and convenient manner than heretofore possible.